Learning HP

[cj-5W]

Hi, so I?m trying to figure out which swap to do over the winter. I have a pretty tired Fiero (I know) and I was thinking the ecotec bolt patterned LLT 3.6 might be a good option since the ecotec F23 axles fit directly into the car. My issue is I have no idea how hard it?ll be to get an LLT out of an auto SUV to run basically standalone. How hard would it be to learn how to tune well enough to let the ECU accept this new arrangement?

I figure I should let people know why I?m doing this. There aren?t any engines near me. None of the standards at least. No 3800sc, no 3.4, not even an LSJ or LNF. I did find an LS4 but that?s more weight and nearly as complicated as an LLT which is in like half the GM SUVs from 2009-2017 and cheaper than even some of the 2.2 ecotecs I?ve been finding. I can fabricate pretty well so I?m not worried about the mounts or exhaust or anything like that. Idk, if it seems like too big an undertaking I might just settle for rebuilding the stock 2.8.

[Alex14SS]

Swapping an LLT 3.6 into your Fiero is definitely possible!!! but it comes with some challenges, especially with the standalone tuning. The LLT is a more modern direct-injection engine, so you'll be working with a more complex ECU compared to older swaps like the 3800sc or 3.4. The biggest hurdle here is getting the ECU to work in standalone mode outside of its original vehicle. This means you'll have to disable a lot of systems like ABS, traction control, and automatic transmission settings if you're using a manual setup.
Learning how to tune well enough to make this happen will require some time, took me about 3-4 years to nail it down but it’s definitely doable. You'll need to familiarize yourself with software like HP Tuners or something similar that has to do with EFI or basic computer programming to access the ECU and start tuning it to accept your setup. You’ll be primarily dealing with fuel, ignition, and torque management tuning. If you’ve got a good grasp of how ECUs manage these systems, you should be able to work through it with some research and practice. HPAcademy is good & Goat Rope Gurage on youtube are good to take a look at. However, keep in mind that direct-injection engines like the LLT can be a bit more finicky with tuning compared to older port-injection systems, especially when dealing with standalone setups.
Given your fabrication skills, the mechanical side of the swap should be manageable, but if tuning and electronic work seems like a big challenge, rebuilding the stock 2.8 or finding a more traditional swap like the 3800sc might be simpler. However, if you're up for the challenge, the LLT could be a fun and unique project.